Lao people are very shy in general and would often refuse to be photographed.  Therefore, ask for permission first before taking pictures. 

Tourism is just taking off and much work still needs to be done both in terms of facilities and education of the local population.

Since most commercial goods have to be imported from Thailand and else where, prices in Laos aren't cheap by any means.  In addition, most tourists seem to be charged with tourist price so be prepared to spend about the same amount, if not more, than as if you were traveling in Thailand.

Drug and prostitution seems to be a problem but it isn't as obvious as Thailand.

UXO doesn't seem to be a problem in Luang Prabang, Vang Vieng and Vientiane but, according to others I have talk to, seem to be a problem further up north.